No. 6(1921) COMMON MOLLUSCS OF SOUTH INDLA. II/ 



depressed and wider in proportion, and rather fragile. Tlie animal 

 is very like a stromb but with the foot even more conspicuously 

 divided into two parts and equally obviously intended for scrambl- 

 ing over the ground at a rapid pace. The operculum is fan-shaped 

 and sculptured. The remarkable characteristic of these shells is 

 the way they disguise themselves by cementing numerous small 

 dead shells to the upper whorls of the spire — the last whorl in adult 

 shells is usually without this decoration. This masking device is 

 intended to deceive possible enemies ; the trick must be effective 

 <"or the shell of Xenophora unlike those of its relatives, the true 

 strombs, is usually thin and easily crushed. Fig, 10 is of a specimen 

 dredged off Malabar. In this particular species the margin of the 

 whorls is beautifully stellate; in others it is thin and foliaceous. 

 On account of this singular habit of collecting shells to conceal 

 their habitations, the Xenophoridae have sometimes been named 

 "Conchologists," those that use fragments of s^one being termed 

 "Mineralogists." They are usually found on level muddy bottom 

 where the surface is strewn with dead and broken shells. 



Of habit wholly dil"ferent are the two families of FalSE- 

 LlMPETS, Capiilidiie and Calyptracidae. The former includes the 

 Bonnet Limpets {Cnpulus and Amathinti). Capiilus has a conical 

 shell not unlike a cap of Liberty, the apex slightly recurved. 

 In our Indian waters, the common species is Amnthina tricostata, a 

 small shell with the apex towards the hinder end and without any 

 trace of the recurved point seen in Capidus. Three stout ribs pass 

 from the apex to the anterior margin, rendering identification easy. 

 It seldom grows more than an inch in length, and is generally 

 found attached to the valves of pearl-oysters in 5 to 6 fathoms in 

 Palk Bay. 



Another interesting Indian Capulid is the little Thyca citocoiicha, 

 parasitic on the under side of the long arms of the star fish Linckia. 

 A muscular plate grips the surface of the starfish and through a 

 hole in this, the pharynx of the parasite works its way into its 

 host. 



The Calyptraeidae include the CUP-AND-SauCER LIMPETS 

 {Calyptraea) and the SLIPPER LhMPETS {Crcpidida). The former 

 are small and conical, the latter, as their English name implies, 

 oval and much flattened. In both an internal plate occurs, the 

 remains of the original spire of the shell. In Calyptraea this plate 



